CD2231

Manufacturer Part NumberCD2231
DescriptionCD2231 Intelligent Two-channel Lan And Wan Communications Controller
ManufacturerIntel Corporation
CD2231 datasheet
 


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Intelligent Two-Channel LAN and WAN Communications Controller — CD2231
Bit 6
EOF – End of frame
The EOF bit indicates that a valid end of frame (7E) character has been received, and
the 7E was not preceded by a 7D.
Bit 5
RxAbt – Receive abort
The rxabt bit indicates that an abort sequence (7D–7E) has been received.
Bit 4
CRC – Receive CRC error
(The terms CRC and FCS are used interchangeably in this document.)
The CRC bit indicates that a frame with a valid end of frame has been received, but
the FCS was not correct. CRC is set only if EOF is set.
Bit 3
OE – Overrun error
The OE bit indicates that the receiver buffer and FIFO have been overrun. At least
one new character has been received, but lost since there was no room available in
the receiver buffer and/or FIFO.
Bit 2
FE – Framing error
The FE bit indicates that a character has been received with an incorrect Stop bit. The
stop bit was ‘0’; it should have been ‘1’.
Bit 1
Reserved – always returns ‘0’ when read.
Bit 0
Break – Break detection
The Break bit indicates that a break has been received. A break is a continuous
sequence of at least ten ‘0’ bits.
Note: 0E, FE, and break are cumulative over the entire packet in PPP mode. This means that the
respective error occurred somewhere in the packet, but did not cause an immediate interrupt.
The following table defines the encoding of RxAbt and FE for an aborted receive frame:
RxAbt
FE
0
0
0
1
1
0
Received abort sequence: x’7D, x’7E
1
1
SLIP Mode
Register Name: RISRl
Register Description: Receive Interrupt Status — Low
Default Value: x’00
Access: Byte Read only
Bit 7
Bit 6
Bit 5
0
EOF
RxAbt
If RxData in IER is set, these interrupts are enabled.
Bit 7
Reserved – always returns ‘0’ when read.
Bit 6
EOF – End of frame
The EOF bit indicates that a valid end of frame (7E) character has been received, and
the 7E was not preceded by a 7D.
Datasheet
Error
None
Not used
Framing error caused a frame abort
Bit 4
Bit 3
0
OE
Intel Hex Address: x’8A
Motorola Hex Address: x’89
Bit 2
Bit 1
Bit 0
FE
0
Break
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